National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Deductive Reasoning
An explanation and description of deductive reasoning in solving problems at this site from The Math Forum. Simple and helpful information.
Cut the Knot
Cut the Knot!: Mathematics: The Science of Patterns
A book excerpt, this page discusses John Venn's "simple, geometric method for checking the validity of syllogisms," with diagrams, examples, and related links.
Organization for Community Networks
Ofcn Lesson Plan: Deductive Reasoning
This OFCN lesson plan offers ideas for incorporating deductive reasoning problems into the classroom.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Logic Definitions: Inductive & Deductive
This site explains what deductive and inductive reasoning is. The site also explains abductive reasoning.